Agronomy Journal Grow Your Career With ASA
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

Published in Agron J 98:423-429 (2006)
DOI: 10.2134/agronj2005.0041
© 2006 American Society of Agronomy
677 S. Segoe Rd., Madison, WI 53711 USA
This Article
Right arrow Abstract Freely available
Right arrow Figures Only
Right arrow Full Text (PDF) Free
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in Web of Science
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Web of Science (5)
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Curnoe, W. E.
Right arrow Articles by Unc, A.
Right arrow Search for Related Content
PubMed
Right arrow Articles by Curnoe, W. E.
Right arrow Articles by Unc, A.
Agricola
Right arrow Articles by Curnoe, W. E.
Right arrow Articles by Unc, A.
Related Collections
Right arrow Crop Growth and Development
Right arrow Industrial Wastes
Right arrow Soil Fertility and Productivity
Right arrow Industrial Waste

Production Papers

Effect of Spring Application of a Paper Mill Soil Conditioner on Corn Yield

William E. Curnoea,*, David C. Irvinga, Charles B. Dowa, George Velemab and Adrian Uncc

a Univ. of Guelph, Kemptville College 830 Prescott Street, Kemptville, ON, K0G 1JO, Canada
b G. Velema, Domtar, Second Street West, Cornwall, ON, K6H 5S3
c Univ. of Ottawa, 451 Smyth Rd. Ottawa, ON, K1H 8M5, Canada

* Corresponding author (bcurnoe{at}kemptvillec.uoguelph.ca)

Received for publication February 2, 2005.

   ABSTRACT
TOP
 ABSTRACT
INTRODUCTION
 MATERIALS AND METHODS
 RESULTS AND DISCUSSION
 SUMMARY
 REFERENCES
 
Use of paper mill residuals as soil amendment on farmland is believed to have a beneficial impact on crop yields and soil quality. The objective of our study was to evaluate the effect of spring applying Domtar Soil Conditioner (SC) (pulp and paper mill waste water treatment residue) to a sandy soil in eastern Ontario, Canada. The effects of SC on corn (Zea mays L.) yields, N concentrations in plants, and post-harvest levels in soil of NO3, P, K, Mg, organic matter (OM), and pH were investigated. The experimental design was a randomized complete block with five treatments, replicated four times. The treatments included two SC rates (15 and 25 Mg ha–1 dry matter: SC15 and SC25), 150 kg ha–1 NH4NO3–N (N150), a composite SC and mineral fertilizer treatment (15 Mg ha–1 dry matter SC and 75 kg ha–1 NH4NO3–N: SC15N75), and a control. The experiment was repeated annually from 1997 to 2001. Addition of SC the spring before planting increased grain yield by 2360 kg ha–1 for SC15 and by 2908 kg ha–1 for SC25 vs. the control. When N was also added (SC15N75), the average increase vs. the control was 3406 kg ha–1. More total N was measured in the corn plants from the plots amended with SC than the control. The SC amendments temporarily increased soil OM but did not increase NO3–N leaching risk. Annual spring application of SC improved corn yield but had little impact on soil nutrient levels, OM, and pH.

Abbreviations: N150, 150 kg ha–1 of NH4NO3–N • OM, soil organic matter • SC, Domtar paper mill soil conditioner • SC15, amendment of 15 Mg ha–1 dry matter soil conditioner • SC25, amendment of 25 Mg ha–1 dry matter soil conditioner • SC15N75, amendment of 15 Mg ha–1 dry matter soil conditioner plus 75 kg ha–1 of NH4NO3–N


   INTRODUCTION
TOP
 ABSTRACT
 INTRODUCTION
MATERIALS AND METHODS
 RESULTS AND DISCUSSION
 SUMMARY
 REFERENCES
 
SEVERAL avenues have been considered for the safe disposal and reuse of paper mill wastes. Landfilling with or without incineration or precomposting is the most common disposal method. They have also been used as landfill covers, given their capability to form relatively impermeable layers when compacted (Moo-Young and Zimmie, 1997), and have been proposed for use in controlling acid mine drainage due to their alkaline pH (Bellaloui et al., 1999; Chtaini et al., 2001). Recovery and reuse of ash following incineration may pose technical difficulties and may not be cost or energy efficient (Koshikawa and Isogai, 2004). Composted paper mill wastes have been proposed as good soil conditioners because of their high OM content and low toxicity (Rantala et al., 1999).

Nutrient content of paper mill residuals can have a beneficial effect on crops (Bellamy et al., 1995). Numerous studies have investigated the role of these materials for increasing the C content of soils and improving the structural stability of soils and their water-holding capacity (Chantigny et al., 1999; Nemati et al., 2000; Zibilske et al., 2000; Foley and Cooperband, 2002). Short-term application to cultivated land has been shown to have no negative impact on the soil properties (Beyer et al., 1997). Long-term heavy application of paper mill sludge had a positive effect on the number and diversity of earthworms at a land restoration site (Piearce et al., 2003). Lignin can be a significant component of paper mill sludge. Pot experiments showed that addition of lignin increased soil pH, cation-exchange capacity, and OM content (Zhang et al., 2004). Forest application of paper mill wastes for hardwood tree growth has given mixed results (Feldkirchner et al., 2003). Phillips et al. (1998) conducted a comprehensive study on the effects of paper mill sludge amendments on the yield of grass and wheat (Triticum aestivum L.) grown on sandy and clay soils. The results of their study indicated notable improvements in the soil fertility parameters but failed to show any significant increase in the yield of grass or wheat at the treated sites. At their experimental site, however, regular mineral fertilization was employed with no credit given to the nutrient content of the sludge.

Long-term research has shown that sewage sludge can have a positive impact on corn yield (Linden et al., 1995) but the same type of research for paper mill residuals is lacking. A pot experiment showed that amending soils with extremely large amounts of paper mill sludge may have a negative impact on the bioavailability of N and P, thus reducing their uptake by corn. This deficiency could be corrected by adding mineral N fertilizer (O'Brien et al., 2002). Treatment of soil with composted paper mill residuals has been shown to reduce the incidence of certain plant diseases independent of the physiological and developmental state of the plants (Vallad et al., 2003), which is in agreement with results obtained with other N-high amendments (Tenuta and Lazarovits, 2004).

A significant unknown associated with the use of paper mill soil conditioners to crops is the rate of release through mineralization of the available nutrients during the cropping season and thus the impact on yield. Some limited research was conducted on decomposition of de-inking paper sludge (Chantigny et al., 1999; Fierro et al., 2000) but these results are not necessarily applicable to other types of paper mill sludge with different C/N ratios.

Because significant research was done on the impact of paper mill biosolids on remediation and restoration of degraded soils, such materials are mostly proposed as soil conditioners. Research is required to assess the agronomic benefits of paper mill residuals to crops in long-term field trials. The objective of our study was to evaluate the effect of land application of a pulp and paper mill residue on corn grain yield during a 5-yr period while monitoring its effects on soil properties.


   MATERIALS AND METHODS
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
RESULTS AND DISCUSSION
 SUMMARY
 REFERENCES
 
Field trials were conducted in eastern Ontario, Canada, during a period of 5 yr (1997–2001) on a Kars sandy loam (eluviated melanic Luvisol). Soil samples were collected each year before planting and after harvest from the 0- to 15-, 15- to 30-, and 30- to 45-cm depths. Composite soil samples of two cores (2.5-cm i.d., 15-cm length) from each plot were used for testing. Samples from the 0- to 15-cm soil depth were tested for pH (1:1 soil/water ratio, Sheldrick, 1984), Olsen-P (measured colorimetrically, Olsen and Sommers, 1982), exchangeable K, Ca, and Mg (NH4OAc-extractable, Sheldrick, 1984), and OM content (loss on ignition, Sheldrick, 1984). Soil samples from all three depths were tested for NO3–N (Keeney and Nelson, 1982). The initial level of NO3–N in the spring of 1997 at the 0- to 15-cm depth was 6.17 mg kg–1 or very low (Ontario Ministry of Agriculture, Food and Rural Affairs, 1995). No NH4 levels were measured at this time. The N level of the soil was not adequate for corn growth in the control treatment (Ontario Ministry of Agriculture, Food and Rural Affairs, 1995). At the start of the trial, the soil had a very high concentration of P (~60 mg kg–1 of Olsen-P) and, therefore, under Ontario recommendations (Ontario Ministry of Agriculture, Food and Rural Affairs, 1995), did not require any supplementary P fertilization. The soil had a pH of 6.9, and an average OM content of 25 g kg–1. The Mg content at 55 mg kg–1 was at the limit of deficiency (Ontario Ministry of Agriculture, Food and Rural Affairs, 1995). The soil also contained 108 mg kg–1 of K, which the Ontario recommendations rate as medium and requires a supplementary K fertilization of 30 kg ha–1 for optimum corn growth and yield (Ontario Ministry of Agriculture, Food and Rural Affairs, 1995). The Ca content of this soil (1330 mg kg–1) was not a limiting factor to corn growth and yield (Ontario Ministry of Agriculture, Food and Rural Affairs, 1995).

Treatments
Treatments included a combination of a soil conditioner (SC) obtained from the secondary treatment stage of a paper mill waste water treatment plant (Domtar Paper Mill, Cornwall, Ontario) and NH4NO3–N. A four-block randomized design with five treatments was used. The treatments included two SC rates (SC15 and SC25), 150 kg ha–1 NH4NO3–N (N150), a composite SC and mineral fertilizer treatment (SC15N75), and an unamended, unfertilized control. Both amendments and fertilizer were applied in the spring before corn planting. The NH4NO3–N was applied according to the recommended N rate for the area (Ontario Ministry of Agriculture, Food and Rural Affairs, 1995). The total mineral content of the SC was measured by atomic absorption (Sheldrick, 1984) and total N was measured by the Kjeldahl method (Bremner and Mulvaney, 1982). All other properties of the SC (Table 1) were measured similarly to soil properties. The dry matter content of the soil conditioner during the trial period, from 1997 to 2001, was constant at 0.3 kg kg–1. Each plot was 3.66 m wide (four rows) and 13.7 m long. The soil conditioner was spread by hand each spring from 18 to 26 April during the 5 yr. In general the only commercial fertilizer applied during the trial was the NH4NO3 that was applied at the same time as the SC on the respective plots; however, the farmer on whose farm the trial was situated applied 185 kg ha–1 K on 3 May 2000 and 300 kg ha–1 K on 30 Apr. 2001. The land was subsequently cultivated and corn was planted. The planting dates during the 5 yr of the trial varied due to weather conditions from 27 April to 5 May. Five corn varieties were used during the trial: Mycogen 2880 in 1997, Novartis 2600 N17-C5 in 1998, Pride 115 in 1999, Mycogen 2242 in 2000, and Pride K115 in 2001. Weed control was practiced during the trial as needed using several Ontario recommended herbicides [s-metolachlor (2-chloro-N-(2-ethyl-6-methylphenyl)-N-[(1S)-2-methoxy-1-methylethyl]acetamide) plus atrazine (6-chloro-N-ethyl-N-(1-methylethyl)-1,3,5-triazine-2,4-diamine), nicosulfuron (2-[[[[(4,6-dimethoxy-2-pyrimidinyl)amino]carbonyl]amino]sulfonyl]-N,N-dimethyl-3-pyridinecarboxamide), prosulfuron (N-[[(4-methoxy-6-methyl-1,3,5-triazin-2-yl)amino]carbonyl]-2-(3,3,3-trifluoropropyl)benzenesulfonamide) plus dicamba(3,6-dichloro-2-methoxybenzoic acid), and isoxaflutole ((5-cyclopropyl-4-isoxazolyl)[2-(methylsulfonyl)-4-(trifluoromethyl)phenyl]methanone) plus atrazine].


View this table:
[in this window]
[in a new window]
  		Table 1. Chemical characteristics of the paper mill soil conditioner (SC).

 
Tissue and Crop Measurements
Tissue samples were taken from all plots at the five-leaf, silking, and grain harvest stage in 1998, 2000, and 2001. At the five-leaf stage, 10 whole plants from non-harvest rows were collected from each plot. At silking, the leaf below and opposite the cob leaf in non-harvest rows was taken from 10 plants in each plot. At harvest, a grain subsample from each plot was collected. No grain sample was collected in 2001 as the corn development was delayed due to drought. Plant material was dried at 37.5°C for 3 to 5 d, ground into a fine powder, and tested for total Kjeldahl N (Bremner and Mulvaney, 1982).

At harvest, the center two rows from the four rows of corn of each plot were harvested by hand, and the cobs were put through a Uni-system combine, which shelled and weighed the grain for each plot. The grain moisture content was measured with a Dickey-John GAC2000 grain analyzer and the grain yield was adjusted to 155 g kg–1 moisture content. The drought of 2001 delayed corn development and the corn had to be harvested as silage. For the silage harvest, plants were collected from two 3-m-long rows; two representative stalks and cobs were selected for each row, dried at 37.5°C for 7 d, and weighed.

Data Analysis
Statistical analyses were carried out using the Genstat statistical software (VSN International Ltd., 2004). Statistical analyses on grain or silage yields for each year were performed by using the one-way ANOVA (analysis of variance) module with blocking to assess the main effect of treatment. When the data for all years were combined (grain yields only), both the main effects of treatment and year and their interaction were analyzed using the two-way ANOVA module with blocking. Because an incomplete set of samples was collected for the soil and plant tissue measurements, the general ANOVA module was used for these analyses. Selected contrasts were used in all these analyses for specific treatment comparison. The potential relationship between grain or silage yield and the different forms of N in the SC and the mineral fertilizer was estimated using multiple linear regression analyses; this allowed an indirect evaluation of the plant availability of SC N. The total amount of N added in the SC treatments varied from year to year as the available and total Kjeldahl N varied; therefore, these values were calculated separately for each year and treatment using the information from Table 1, and they were used for the multiple regression analyses. Graphics were generated using the Minitab (Minitab, 2004) statistical package. Differences were declared significant at P < 0.05.


   RESULTS AND DISCUSSION
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS AND DISCUSSION
SUMMARY
 REFERENCES
 
Corn Yield
Corn yields are presented in Table 2. Analysis of variance indicated that both treatment type and year had a significant effect on the grain corn yield in 1997 to 2000 (P < 0.001 for both factors and their interaction). The treatment type also had a significant impact on the silage yield in 2001 (P = 0.015). Every treatment led to significant increases in the grain yield (1998–2000) or silage yield (2001) compared to the unamended and unfertilized control. Addition of SC at the two rates led to an average increase in grain yield (1997–2000) of 2360 to 2908 kg ha–1. In the first year of the trial (1997), the grain yield was greater than the control for every treatment (Table 2) but extreme variability in grain yield due to late drought resulted in a statistically insignificant means separation, except for the SC15N75–control comparison (Table 3). The greatest yield was consistently obtained from the SC15N75 treatment, which combined the SC and NH4NO3–N (Table 2); however, in all years except 2000, this treatment was statistically comparable with the SC15 treatment, which had the same amount of SC but lacked the fertilizer N (Table 3). The N150 treatment resulted in yields that were generally inferior to the ones obtained with any of the treatments that incorporated SC amendments, although not statistically different from the yields obtained with the SC15 treatment. The results suggest an interaction between the nutrients provided by the SC and the mineral fertilizer even if no more than staggered availability of nutrients to the corn crop during the season. Nevertheless, the significance of this interaction is largely dependent on other environmental factors that may regulate the availability of nutrients from the SC and also modify crop requirements during the season.


View this table:
[in this window]
[in a new window]
  		Table 2. Average corn grain yield (1997–2000) and silage yield (2001) for each treatment.

 

View this table:
[in this window]
[in a new window]
  		Table 3. Contrasts for grain yield (1997–2000) and silage yield (2001) under different treatments.

 
The two SC treatments (SC15 and SC25) produced statistically equivalent yields (Table 3).

An attempt to evaluate the significance of the N applied with the soil conditioner was made by fitting to yield a multiple linear regression that incorporated either the total Kjeldahl N or the total available N (NH4–N and NO3–N) in the SC (SC-TKN or SC-N) and the mineral fertilizer N (Table 4). The SC-N, which is mostly in the form of NO3–N (Table 1) is available immediately to the crop. The regression analysis allocated a response of 40 to 60 kg yield for each 1 kg of SC-N; however, this is probably an overestimate that accounts for the associated slowly mineralized organic N found in the SC. Each 1 kg of the similarly readily available NH4NO3–N accounted for only an increase of 10 to 20 kg yield. On the other hand, the regression analysis allocated up to 9 kg yield to each 1 kg of SC-TKN (Table 4). These values are about one-half of the NH4NO3–N values and they are probably closer to reality as they account for the easily available N—the N mineralized during the cropping season and the N that remains in the OM not mineralized during the season. If we assume 40% of the SC-TKN to be mineralized throughout the growing season, then the SC-N use efficiency becomes similar to that of the fertilizer NH4NO3–N. The early summer drought of 1997 limited the impact of the readily available NH4NO3–N and thus led to low N use efficiencies (Table 4).


View this table:
[in this window]
[in a new window]
  		Table 4. Grain yield (1997–2000) and silage yield (2001) as a function of the land-applied soil conditioner N and mineral fertilizer N.

 
Nitrogen Uptake Patterns
In general, the total N content measured in the plant tissues was greater in the plants from the treated plots than the plants from control plots at both five-leaf and silking stages (Table 5). A direct comparison between the N150 and the SC25 treatments indicated that the SC25 treatment led to a significant increase in the concentration of N in the plant tissues at the two stages in 2000, but during 2001 the differences were not statistically significant (Table 6). No differences in plant N for the five-leaf stage during 2000 and 2001 were observed between the SC15 and SC25 treatments; however, significant differences in plant N for the silking stage occurred between the SC15 and SC25 treatments during 2000 and 2001. The N content in the harvested grain was similar for all treatments including the control (Table 6). This indicates that the supplementary N available on the treated plots led to increased yield but not to higher N concentration in the grain. In general, there is no evidence to suggest that the addition of SC may have resulted in N immobilization (O'Brien et al., 2002) or lack of N availability to corn. On the contrary, both N in plant tissues and yield measurements show that SC addition increased the N availability to corn when compared with the control. This was expected, as the C/N ratio of the SC used was significantly lower than the generally accepted average of 50 or higher for paper mill residuals (Rynk, 1992).


View this table:
[in this window]
[in a new window]
  		Table 5. Average total Kjeldahl N in plant tissues. Plant tissue measurements were conducted only in 1998, 2000, and 2001.

 

View this table:
[in this window]
[in a new window]
  		Table 6. Selected contrasts for total Kjeldahl N (TKN) in plant tissues at three stages.

 
Residual Nitrate in Soil
The concentration of NO3–N in the first 15 cm of the soil profile increased with time for the SC treatments and increased with increased SC application rate (Fig. 1 ). The increase with time may suggest an effect of the repeated application of SC on the total pool of mineralizable organic material. This increase was not mirrored at the two other depths, up to 45 cm, that were sampled and analyzed. The NO3–N concentration was consistently under 10 mg kg–1 (Fig. 1). This suggests that little NO3–N leaching risk was associated with the addition of the pulp and paper SC to the corn crop on this soil.


Figure 1
View larger version (47K):
[in this window]
[in a new window]
  		Fig. 1. Average NO3–N measured in soil at harvest. Treatments: N150—150 kg ha–1 of NH4NO3–N; SC15—15 Mg ha–1 dry matter paper mill soil conditioner; SC15N75—15 Mg ha–1 dry matter paper mill soil conditioner and 75 kg ha–1 of NH4NO3–N; SC25—25 Mg ha–1 dry matter paper mill soil conditioner.

 
Soil Fertility Measurements
The soil had a high Olsen-P level at the start of the trial. Olsen-P is generally associated with its availability for crop uptake in soils with lower available P levels (Hedley et al., 1995). The soil Olsen-P was greater than the control only for the SC25 treatment (Tables 7 and 8) during the 5-yr period. While some of the increase in available P may have been associated with the addition of the SC amendment, it may also have been partially related to the increased mass of crop residues and increased P mobilization through microbial activity after addition of supplementary nutrients (Sharpley, 1985; McLachlan et al., 1988; Lee et al., 1990).


View this table:
[in this window]
[in a new window]
  		Table 7. Soil fertility indicators measured after harvest: values after 4 and 5 yr of treatment.

 

View this table:
[in this window]
[in a new window]
  		Table 8. Selected contrasts for soil fertility indicators.

 
While exchangeable K values in the soil increased in 2000 and, most noticeably, in 2001 in all plots as a response to the supplementary fertilizer K added by the farmer (data not shown) no significant impact on the exchangeable K levels could be specifically attributed to any of the treatments (Tables 7 and 8).

The only external source for Mg on the trial plots was the SC (Table 1) and possibly atmospheric deposition (Johnson and Todd, 1987). In general, no treatment impact could be noted for the concentrations of exchangeable Mg in any year of the trial (Table 7). In 2000 and 2001, the measured Mg decreased for all treatments including the control. While the decrease can be partially linked to the lower total Mg concentration in the SC (Table 1), the cause for the decrease in the control plots is less obvious. The grain yield reached its maximum in 2000 for the SC treatments and actually decreased in 2000 for the control and N150 treatments (Table 2). These are also the years when supplementary K fertilizer was added by the farmer. As both minerals are part of the cation-exchange complex, it is likely that competitive retention may have caused the lower Mg levels in the soil. While the SC-amended plots received reduced quantities of Mg in 2000 and 2001 (Table 1), the control and the N150 plots received none. It is known that Mg fulfills the role of enzyme activator for enzymes involved in the transfer of phosphates and carboxyl groups (Marschner, 1995, p. 280–282) and thus its absence will lower the use efficiency of available P, slowing plant metabolism. In general, a soil with less than ~60 mg kg–1 Mg is considered to be deficient and Mg deficiencies have been shown to be accentuated by excess K (Camberato and Pan, 1999). While this may be part of the explanation for the lower yields on the control and the N150 plots, insufficient information was available to thoroughly elucidate this issue.

Generally, soil OM tended to be greater in the soils amended with SC (Table 7); however, while this was true for any given year, no statistically significant effect could be associated with the SC treatment during the 5 yr of the trial (Table 7). This was different from results reported by O'Brien et al. (2002) from a very short-term laboratory study, but similar to the observations of Beyer et al. (1997), who noted that the increase in the total OM content following land application of paper mill residues to a sandy soil disappeared within 1 yr. Nevertheless, N mineralization depends on the initial chemistry of the organic material (Rowell et al., 2001). The SC used in our experiment had a relatively low C/N ratio (Table 1). Hence, our results suggest that SC organic material mineralizes from year to year.

The pH of the SC was slightly more alkaline than the soil pH; at the end of the growing season, however, there was no measurable impact on the pH of the soil that received SC amendments (Table 7). In contrast, the NH4NO3–N treatments significantly decreased soil pH (Tables 7 and 8).


   SUMMARY
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS AND DISCUSSION
 SUMMARY
REFERENCES
 
Land application of paper mill SC significantly increased corn yields even in the absence of mineral fertilizer. Leaf total N measurements indicated that more N was available for uptake by the corn plants during the growing season where SC or NH4NO3–N was added compared with the control. The soil OM content increased each year during the application of SC; however, little evidence for long-term accumulation of OM was noted. Low NO3–N concentrations in the deeper soil layers posed no risk to water resources and no SC-related changes were noted in the concentrations of P, K, Mg, or soil pH.


   ACKNOWLEDGMENTS
 
The authors would like to thank Brent Winters, Greenfield Environmental Services, for his technical assistance. Partial funding for this research was provided by Domtar Inc. and the Ontario Ministry of Agriculture and Food.


   REFERENCES
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS AND DISCUSSION
 SUMMARY
 REFERENCES
 




This article has been cited by other articles:


Home page
 J. Environ. Qual.Home page
G. W. Price and R. P. Voroney
Papermill Biosolids Effect on Soil Physical and Chemical Properties
J. Environ. Qual., November 1, 2007; 36(6): 1704 - 1714.
[Abstract] [Full Text] [PDF]

This Article
Right arrow Abstract Freely available
Right arrow Figures Only
Right arrow Full Text (PDF) Free
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in Web of Science
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Web of Science (5)
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Curnoe, W. E.
Right arrow Articles by Unc, A.
Right arrow Search for Related Content
PubMed
Right arrow Articles by Curnoe, W. E.
Right arrow Articles by Unc, A.
Agricola
Right arrow Articles by Curnoe, W. E.
Right arrow Articles by Unc, A.
Related Collections
Right arrow Crop Growth and Development
Right arrow Industrial Wastes
Right arrow Soil Fertility and Productivity
Right arrow Industrial Waste

HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
The SCI Journals Crop Science Vadose Zone Journal
Journal of Natural Resources
and Life Sciences Education		 Soil Science Society of America Journal
Journal of Plant Registrations Journal of
Environmental Quality		 The Plant Genome